Which of the following is not a method of controlled tipping?

Controlled tipping or sanitary landfill Most satisfactory method of refuse disposal where suitable land is available. "Modified sanitary landfill" has been applied to those operations where compaction and covering are accomplished once or twice a week. 3 methods Trench method: Where level ground is available. Ramp method : Terrain is moderately sloping. Some excavation is done to secure the covering material. Area method: This method is used for filling land depressions, disused quarries and clay pits.